1. Field of the Invention
The present invention relates generally to radio telephone systems and their control methods, and more particularly, to radio telephone system which is suitable in such applications as in pastures or golf courses where a relatively small number of radio telephone sets are used to cover a wide communication area with a low communication traffic, and also to a method of controlling the system.
2. Description of the Prior Art
A radio telephone system of the type referred to is arranged as shown in FIG. 12 so that, as well known, L of wired telephone lines 1 (1A to 1L) are connected to a controller 2 which in turn is connected through N of connection cables 3 (3A to 3N) to N of connectors 4A to 4N, the connectors 4A to 4N being coupled through their radio communication circuits with M of radio telephone sets 5A to 5M, so that speeches or communications can be realized between the radio telephone sets 4A to 4M and the associated wired telephone lines 1A to 1L through the connectors 4A to 4N under control of controller 2.
With such an arrangement, if an incoming call to the radio telephone set 5A appears on, for example, the wired telephone line 1A, then the controller 2 sends the incoming signal to the connector 4A having a radio zone in which the radio telephone set 5A is present, to cause the connector 4A to call the associated radio telephone set 5A, so that when user of the radio telephone set 5A gives an off-hook response, the system can be put in its speech enable state. In this case, calling of the radio telephone set 5A from the connector 4A is realized by transmitting to the radio telephone set 5A an incoming-call signal in which a predesignated identification data (ID code) is contained.
The same explanation holds true for the case where a calling operation is performed at the radio telephone set 5A. That is, when the connector 4A receives a calling signal from the radio telephone set 5A, the connector 4A judges whether or not the identification data included in the received calling signal coincides with the identification data of the radio telephone set 5A itself. If the connector 4A finds an identification data coincidence, then it advances the subsequent line interconnection sequence to connect the radio telephone set 5A with the wired telephone line 1A.
In the case where the radio telephone set 5A is moved from the radio zone of the connector 4A into the new radio zone of, for example, connector 4B, the radio telephone set 5A causes the controller 2 to perform a position registration operation with respect to the new radio zone so that the controller 2 transfers the incoming call for the radio telephone set 5A to the connector 4B and the connector 4B calls the radio telephone set 5A. In the same manner as in the above case, the radio zone of the radio telephone Set 5A may be used as expanded even to a zone other than the radio zone of the connector 4A.
The above radio telephone system, which realizes the expansion of the radio zone under control of the controller 2 managing the positions of the radio telephone sets 5A to 5M, is effective when the number of the radio telephone sets 5A to 5N is larger than the number of the connectors 4A to 4N and complicated control is required; but when the number of the radio telephone sets is smaller than the number of the connectors 4A to 4N, the system has a problem that the system is not economical because many of the functions of the controller 2 become useless.